The investigators have developed a method for measuring the N7-guanine (N7-G) DNA adducts of ethylene oxide and styrene. Since ethylene oxide and styrene are widely used in industry and are tumorigenic in animals, the investigators propose to apply the method to blood samples of workers exposed to these agents occupationally. If such DNA adducts can be then the project may lead to a better understanding of where to set occupational exposure limits for those working with these chemicals. In their method, which they claim is both convenient and powerful, the N7-G adducts are easily harvested from DNA by simply heating the DNA in water. Simple reagents and steps are then used to derivatize and purify the adducts prior to detection by mass spectrometry. The same method can in the future find use in the detection of other simple alkyl and hydroxalkyl N7-G adducts formed by industrial or environmental chemicals other than ethylene oxide or styrene.